The invention concerns a biopsy needle, in particular a precision biopsy needle, for removing liquid-containing tissue samples. More particularly, the invention is directed to biopsy needles having a hollow needle body that receives the tissue sample and an internal plunger that is movable inside the needle body. The invention further concerns a biopsy apparatus having a hollow needle body for piercing the tissue that is to be biopsied.
Conventional biopsy needles, in particular conventional precision biopsy needles, are provided for removing tissue samples from the interior of the body or from the internal region of organs. Precision biopsy needles make it possible to remove tissue biopsy specimens with a very small diameter on the order of approximately 0.5 mm. The removed piece of tissue is usually located in the front region of the needle body, since it is almost impossible to receive more biopsy specimen without damaging the biopsy specimen through compression.
For further processing of the removed tissue sample, for example, in order to fix and embed it, the piece of tissue must be removed from the needle tip.
Especially with precision biopsy samples having diameters of approximately 0.5 mm or less, such removal is problematic due to the small diameter and low inherent strength of most tissues. Manipulation during transfer of the small pieces of tissue is also critical because of the risk of damage to the large- and small-scale tissue structure, for example, if a tweezers or other mechanical aid is used. There also exists the danger than the small-volume sample material might dry out during manipulation.
In accordance with one aspect of the invention, there has been provided a biopsy needle for removing liquid-containing tissue samples comprising: a needle body having a first hollow bore section defined by an inner wall, for receiving the tissue sample; an internal plunger axially movable inside the bore section of the needle body; and a hollow, generally cylindrical removable sample receiving element positioned between the inner wall of the needle body bore section and the movable internal plunger.
Preferably, the sample receiving element comprises a hydrophilic material having a high tensile strength, i.e., to permit it to be pulled out of the needle without tearing. The sample receiving element may comprise a porous polymeric material or a cellulose material. The needle body preferably includes a needle head having a cutting edge. The sample receiving element is preferably configured so that, when it is positioned in the needle body, it serves as a lining and has an inside diameter substantially the same as an inside diameter of the needle head.
Preferably, the needle body includes a pair of openings, through which the sample receiving element may be inserted and removed. The needle head is preferably configured to be separated from the rest of the needle body. The inside diameter of the needle head near the cutting edge is slightly smaller than the inside diameter of the sample receiving element. wherein the internal plunger includes a tip for cutting the tissue to be penetrated.
In an alternative embodiment, a biopsy apparatus is provided. The apparatus includes a hollow needle body for piercing a tissue to be biopsied. The needle body includes an internal cavity for receiving a removable sample receiving element. The sample receiving element preferably comprises a material having a high tensile strength. The sample receiving element also preferably comprises a hydrophilic material. In a preferred arrangement, the sample receiving element comprises an expandable or liquid swellable material.
In accordance with another aspect of the invention, there has been provided a method for taking a liquid-containing biopsy tissue sample, comprising: positioning a hollow, generally cylindrical removable sample receiving element into a needle body having a first hollow bore section defined by an inner wall, along the inner wall of the needle body bore section; inserting the needle body into the tissue region from which the sample is desired; relatively moving the needle body and an internal plunger axially movable inside the bore section of the needle body to draw into the sample receiving element a sample of tissue; withdrawing the needle from the tissue; and removing the sample receiving element and sample contained therein from the needle body.